Costa E Silva João, Borralho Nuno M G, Potts Brad M
Departamento de Engenharia Florestal, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017, Lisboa Codex, Portugal.
Theor Appl Genet. 2004 Apr;108(6):1113-9. doi: 10.1007/s00122-003-1524-5. Epub 2003 Dec 16.
The first estimates of the importance of epistatic effects within Eucalyptus globulus were obtained from analysis of clonally replicated full-sib progeny tests grown in Portugal. Parents comprised diverse selections from the Portuguese landrace. Variance components were estimated for 4-year-old diameter growth and pilodyn penetration, an indirect measure of wood density, both key traits in the pulpwood breeding objective. The experimental components of variance were used to estimate heritabilities and proportions of the phenotypic variance due to dominance and epistasis. The additive variance was the only significant genetic component affecting either diameter or pilodyn. Estimates of the additive, dominance and epistatic effects accounted for 8-10%, 0-4% and 0.4% of the phenotypic variance in diameter, and for 11-17%, 0% and 5% of the phenotypic variance in pilodyn, respectively. A comparison of residual coefficients of variation within seedling and cloned progenies indicated that C effects within clones were not a serious source of random variability. Despite the test sites encompassing a diverse range of locations, no important genotype by environment interaction was detected. The results suggested that an improvement strategy combining both recurrent selection for additive genetic merit and clonal testing may be adequate for optimizing genetic gains from this genetic base.
对蓝桉上位效应重要性的初步估计，是通过对在葡萄牙种植的克隆复制全同胞后代试验进行分析得出的。亲本包括来自葡萄牙地方品种的不同选择。对4年生的直径生长和皮洛氏硬度计穿透率（木材密度的间接测量指标）进行了方差成分估计，这两个都是纸浆材育种目标中的关键性状。利用方差的实验成分来估计遗传力以及由显性和上位性引起的表型方差比例。加性方差是影响直径或皮洛氏硬度计的唯一显著遗传成分。加性、显性和上位效应的估计分别占直径表型方差的8 - 10%、0 - 4%和0.4%，以及皮洛氏硬度计表型方差的11 - 17%、0%和5%。对幼苗和克隆后代内的剩余变异系数进行比较表明，克隆内的C效应不是随机变异的严重来源。尽管试验地点涵盖了各种不同的位置，但未检测到重要的基因型与环境的相互作用。结果表明，将针对加性遗传优点的轮回选择和克隆测试相结合的改良策略，可能足以从该遗传基础中优化遗传增益。
